The proposed work is a continuation of efforts to analyze the developmental genetic components of the sexual reproductive apparatus of Neurospora. Previous work has indicated that a close relationship of spindle pole bodies and spore delimiting membranes is essential if normal spore excision is to occur. Electron microscopy will be used to probe the generality of this observation by comparison of normal strains and newly found mutants that fail to excise spores properly. Previously studied mutants whose spore delimiting membranes either fail to assemble or to assemble normally will be analyzed for possible differences in the protein components of the membranes. Some differences have already been shown. Finally, in reference to our recent observation that the spore excision pattern in N. tetrasperma is markedly altered in mutants resistant to p-DL-fluorophenylalanine and methyl benzimidazol-2-yl carbamate, the ultrastructural effects and biochemical effects of the mutations will be analyzed.